We have further developed a scheme utilizing small angle neutron scattering (SANS) to probe interactions between macromolecules in highly concentrated protein solutions. Using this technique we have systematically studied properties of bovine serum albumin (BSA) samples to test the theoretical analysis thus is used to extract molecular size and charge from experimental data. Studies also were performed on hemoglobin (Hb) solutions, the results of which were employed to devise techniques for examining protein interactions within intact erythrocytes and other biological vesicles. The contrast match point for vesicle membranes has been determined and detection of protein aggregates in deoxygenated sickle red blood cells was demonstrated. Several investigations based on this methodology now are in progress. We have undertaken investigations into the properties of polymer networks and related amorphous structures. For this purpose we have developed mathematical models to describe the formation of cytoskeletal networks. These allowed us to investigate complex relationships between nucleation. Polymerization, crosslinking, chain termination and chain scission procedures were developed for obtaining "elasticity contours" (e.g., dependences of shear modulus on Ca++ concentration), which are needed for theories of cell movement. Quantitative gelation assays for assessing the activity or cytoskeletal binding proteins also were analyzed.